ion-sound/sh-interrupt

1) Link or copy the shell to test to "./testshell", then run the tests
like this: `./test01.sh`

2) Please keep in mind that the sigint catcher program remaps SIGQUIT
to C-g. When a script fails, it is possible that your terminal is left
with these changes. Either you have to be careful and reset the
terminal when it is needed or keep in mind that you might have to use
C-g insted of C-\ for SIGQUIT.

3) Some background jobs are started and are supposed to be killed by a
working shell. You wouldn't read this if you weren't concerned about
the quality of your shell, so you probably have some runaway jobs when
done with the tests. Make sure you `ps` for all jobs attached to your
terminal when you're done. I just discovered a `wc -c /dev/zero`
running on my machine since almost a week ago :-)

4) The program ./hardguy lasts 20 seconds it is not catched by the
surrounding shell, no matter what happens. Patience, no need to kill
it.

5) Some examples need the -T switch I just committed to
FreeBSD-current's /bin/sh (immediate execution of traps).

mkdep.sh tests mkdep, which is an example of a program that is
implemented as shell script and need to kill itself in a trap
handler. It should just be interruptable by the first SIGINT.

test??[ab].sh are subshell neede for other tests, but cann be called
directly as well.